Conventional concrete block construction uses rectangular blocks, generally having one or more cavities through the blocks from top to bottom. A layer of mortar is thrilled onto a foundation and a course of closely spaced blocks are laid on the layer, with additional mortar applied between the contiguous block ends. Another layer of mortar is applied to the top of the first course and additional courses are similarly laid, generally staggering the block ends from course to course. Great care and skill is required to achieve level courses and a truly vertical wall. Because of the time and skill required for such construction, costs are high. These blocks have vertically aligned cavities that can be filled with rebar and concrete to reinforce the wall.
Various types of mortarless interlocking blocks have been devised in the past to facilitate the construction of block walls and other structures. Most such blocks have been very expensive to produce since the interlocking portions, usually grooves or protrusions, are normally cut into the blocks after they have been formed by molding. Further, it is difficult to maintain the required tight tolerances required for accurate construction of large walls or other structures through the molding and cutting steps. The prior blocks often required additional finishing or grinding steps to meet the require tolerances.
Excellent interlocking mortarless building blocks overcoming many of these deficiencies are describe in U.S. Pat. Nos. 3,888,060, and 4,640,071, both granted to the inventor of the present invention. Those blocks have been used successfully for many years. These blocks are assembled in courses, with the block joints staggered and continuous vertical open cells into which reinforcing bars ("rebar") and concrete grout can be inserted. While highly effective, these blocks require that rebar be inserted in lower courses, with blocks in later courses lifted over the ends of the rebar as the structure advances and wet concrete is periodically poured into the cells containing the rebar. Thus installing blocks over rebar can be a significant problem with tall structures.
Also, three or more different block configurations may be required for many structures, such as walls, buildings with openings and floor panels connected to the block wall. Additional block configurations require the manufacture of additional expensive molds and increased cost and time in changing molds in a block making machine and maintaining and inventory of the different block configurations.
Many of building walls made from these blocks have excessive thermal conductivity across the wall, which is a particular problem in cold climates where the interior is heated or in hot climates where the interior is cooled. Heat transmission across such a wall varies between areas where the blocks have large open internal cavities and areas where the cavities are filled with concrete and rebar reinforcements. In addition to the undesirable loss of interior heating or cooling through the wall, with heated buildings, cold spots may form on the interior of the wall that condense water from the inside atmosphere and run down the wall.
Attempts have been made to fill the block cavities with loose fiberglass insulation, loose foam particles, foamed in place materials, etc. Loose insulation tends to settle and provide very uneven insulation with resulting cold spots. The insulation cannot be placed in block cavities that are to be filled with concrete and rebar reinforcements, again resulting in thermal gradients along the wall, with widely varying interior wall temperatures at insulated and uninsulated areas.
Therefore, there is a continuing need for improvements in these successful block systems to permit lower cost block manufacture and lower cost, more rapid structure assembly from the blocks, the ability to provide thermal insulation in all blocks while still permitting the introduction of reinforcing concrete and rebar into all or some of the blocks and to place such reinforcement with insulation already in place.